Use algorithms optimized for row-major array layout

Enable algorithm for row-major format code generation and simulation

Model Configuration Pane: Math and Data Types

Description

The Use algorithms optimized for row-major array layout parameter enables optimized algorithms for row-major format code generation and corresponding row-major algorithms for model simulation for certain blocks.

Settings

off (default) | on

When Array layout (Simulink Coder) is set to Row-major, the code generator uses algorithms to maintain consistency of numeric results between the simulation and the generated code. Sometimes, the generated code for these algorithms might be inefficient. You can enable the Use algorithms optimized for row-major array layout configuration parameter to enable efficient algorithms that are optimized for certain blocks. The Use algorithms optimized for row-major array layout parameter affects the simulation and the generated code.

This parameter affects only these blocks:

Sum of Elements
Product of Elements
n-D Lookup Table
Interpolation Using Prelookup
Direct Lookup Table (n-D)

For these blocks, the column-major and row-major algorithms might differ in the order of output calculations, possibly resulting in slightly different numeric values.

On

When Array layout is set to Row-major, this parameter enables the use of efficient algorithms that traverse the data in row-major order. The generated code is efficient.
When Array layout is set to Column-major, this parameter enables the use of algorithms that traverse the data in row-major order. The generated code is inefficient.

Off

When Array layout is set to Row-major, the code generator uses algorithms that traverse the data in column-major order. The generated code is inefficient.
When Array layout is set to Column-major, the code generator uses algorithms that traverse the data in column-major order. The generated code is efficient.

Tips

When Array layout is set to Row-major, the row-major algorithm operates on table data that is contiguous in memory. This table data leads to faster cache access, making these algorithms cache-friendly.

This table summarizes the relationship between array layout and cache-friendly algorithms. It is a best practice to use the algorithm that is optimized for the specified array layout to achieve good performance. For example, select Use algorithms optimized for row-major array layout when the Array layout is set to Row-major for code generation.

`ArrayLayout`	`UseRowMajorAlgorithm`	Algorithm Applied
`Column-major`	`'off'`	Efficient column-major algorithm Recommended
`Row-major`	`'off'`	Inefficient column-major algorithm Not recommended
`Column-major`	`'on'`	Inefficient row-major algorithm Not recommended
`Row-major`	`'on'`	Efficient row-major algorithm Recommended

Recommended Settings

Application	Setting
Debugging	No impact
Traceability	No impact
Efficiency	No impact
Safety precaution	No impact

Programmatic Use

Parameter: UseRowMajorAlgorithm

Type: character vector

Value: 'on' | 'off'

Default: 'off'

Version History

Introduced in R2018b